Cord Blood Mercury and Early Child Development: Effects of the World Trade Center

(at 36 months of age for PDI and 48 months for VFIQS) as a function of pre natal mercury exposure (corrected for maternal fi sh intake during pregnancy) resulting from potential exposure after the World Trade Center (WTC) disaster. This timely and interesting study took into consideration maternal variables known to infl uence cord Hg (possibly reflecting fish consumption) and also controlled for most of the known maternal characteristics that could affect neuro-developmental outcomes. However, two of the most important variables in the context of infant exposure and neurodevelopment were left out of the model: early (pregnancy and post natal) thimerosal-Hg exposure and the mode of feeding (Dórea 2007). Th e children enrolled in the study were delivered at term in Lower Manhattan (New York, NY, USA) after 11 September 2001. Coincidently, around this time, the U.S. health authorities decided to withdraw thimerosal (as a preservative) from infants' vaccines (Geier and Geier 2005). Th is decision generated controversy that impacted immunization and also demanded epidemio-logic studies to evaluate the neurotoxic consequences (Th ompson et al. 2007). Th erefore, Lederman et al.'s (2008) study cohort probably contained not only children immunized with thimerosal-containing vaccines (TCV) but also some mothers using products containing thimerosal during pregnancy (e.g., Rh-negative mothers taking anti-RhoD immune globulins) (Geier et al. 2008). Although TCV are no longer used in the United States and other developed nations, they are used elsewhere in under developed countries, exposing infants to varied ethyl mercury (EtHg) concentrations (depending on the vaccine manufacturer) and a wide range of doses, depending on the infant's weight (Dórea and Marques 2008). This controversial issue (safety of early exposure to EtHg and neurodevelopment) has only recently been considered in epidemiologic studies of U.S. children (Thompson et al. 2007). Although the beneficial effect of (maternal) fish consumption is a concept emerging in most recent studies that have explored the neuro develop ment of children , the few studies of TCV's effects on neuro development have been inconclusive in the United States. Th e most recent study neither adjusted for breast-feeding nor for additional pre natal methylmercury (MeHg) exposure from maternal fi sh consumption, but they attributed the conflicting outcomes to chance (Thompson et al. 2007). However, the additional EtHg exposure from post natal TCV may contribute to a relative increase in infant hair-Hg (Marques et al. 2007). Coupled with that, the Faroese cohort studies (Grandjean et al. 1995; …